Most people carry a variety of paraphernalia with them such as keys, nail clippers, wallets, glasses and other small objects which are bulky and tend to distend the pockets when carried in that fashion. In addition to these articles, musicians have a variety of accessories accompanying their instruments which must be accessible periodically, or regularly, when they play. In an orchestral setting or even when practicing, no such place currently exists and the musician may keep reeds, extra mouthpieces, resin, a reed knife, mutes, guitar picks, extra strings, a tuning form or castanettes (not usually all of the above), stewn about the chair in which the musician sets or resting on the sheet music stand, thereby interferring with the sheet music.
Clearly, musicians thus have a need beyond that of the average person for convenient temporary storage of their accessories in a fashion that makes they readily available for use with their instruments while playing.